(1) Field of the Invention
This invention relates to a substrate treating apparatus for performing a series of treatments of substrates such as semiconductor wafers, glass substrates for liquid crystal displays, glass substrates for photomasks, and substrates for optical disks (hereinafter called simply “substrates”).
(2) Description of the Related Art
Conventionally, a substrate treating apparatus is used to form a resist film on substrates, allows the substrates having the resist film formed thereon to be exposed in a separate exposing machine, and develops the exposed substrates. Specifically, the substrate treating apparatus includes a plurality of blocks each having various chemical treating units such as coating units for forming resist film and heat-treating units arranged with a single main transport mechanism. This apparatus transports substrates to each block to be treated therein (as disclosed in Japanese Unexamined Patent Publication No. 2003-324139, for example).
The conventional apparatus with such a construction has the following drawback.
In the conventional apparatus, the main transport mechanism goes through five to 10 transporting steps for treating each substrate in its block, and each transporting step takes several seconds. Supposing that the number of transporting steps is six and each step takes five seconds, the throughput in the block can be raised up to 30 seconds per substrate (or 120 substrates per hour). However, there is not much room for reducing the number of transporting steps for the single main transport mechanism or shortening the time for each transporting step. Hence, it is difficult to achieve a further improvement in throughput of each block. It is therefore difficult to improve the throughput of the entire apparatus. One possible solution is to employ multiple main transport mechanisms. However, an increase in the number of main transport mechanisms in each block entails the inconvenience of increasing the chemical treating units and heating units, thereby enlarging the footprint.